Many drummers have recognized that it is difficult to practice the drums at home because drums are quite loud. To remedy this problem, drummers have relied on electronic versions of a drum kit. Many of these electronic drum kits use rubber pads to simulate drums. These rubber pads have force sensors that sense when the pad has been struck, and how hard it has been struck.
In addition to drums, a typical drum kit also has cymbals. In the case of an electronic drum kit, these cymbals are replaced by rubber disks that are mounted on a pole in much the same way a real cymbal would be mounted. The rubber disk has force sensors like those used in the drums.
When practicing using an electronic drum set, the drummer usually wears headphones that are connected to an amplifier. When the drummer strikes a rubber pad, a corresponding sound is played out the amplifier so that the drummer has the illusion of playing a real drum. Similarly, when the drummer hits the rubber disk, a corresponding cymbal sound is played out the amplifier.
In an acoustic drum kit, the sound that a drum or cymbal makes depends to some extent on where it is hit. In the case of electronic drum kits, this variation in sound can be simulated by having multiple force sensors on the rubber pad. When the rubber pad is struck, the differential forces sensed at each sensor can be used to triangulate the likely position of the strike. With this position known, a corresponding sound can be played through the headphones.
The resulting system creates a fairly convincing simulation of a real drum kit, at least as far as the sense of hearing is concerned. However, there are difficulties with the drummer's haptic feedback. This is because the elements of an electronic drum kit do not feel quite like their acoustic counterparts.
For some elements, the difference is tolerable. For example, since a bass drum is played by foot pedal anyway, the fact that one is hitting a rubber pad is not so noticeable. For other drums, the difference is noticeable but tolerable. However, the rubber disk that masquerades as a cymbal is completely unconvincing. A suspended rubber disk simply does not feel even remotely like a cymbal.
One way to retain the feel of a cymbal while avoiding its excessive volume is to use a “deadened cymbal.” A deadened cymbal is intended to feel like a real cymbal but to be much quieter.
One way to make a deadened cymbal is to perforate the cymbal's metal surface. Such perforated cymbals retain much of the feel of conventional cymbals, but without as much sound. Perforated cymbals provide good haptic feedback to the drummer.
Another way to make a deadened cymbal is to coat the perforated cymbal with a sound-deadening material to further reduce the volume. This compromises the haptic feedback somewhat. But the result is still far superior to a rubber disk.
A difficulty that arises is that a cymbal of this type is still an acoustic instrument. A drummer who is wearing headphones may not be able to hear the cymbal very well. In fact, since the cymbal was designed to be quiet, he may not hear it at all.
One solution to this problem is to do what is done with a singer's voice: use a microphone. Thus, one can place a microphone near the cymbal to generate an electronic analog signal that can be passed to the amplifier and mixed with the drum signals. The drummer will then be able to hear the cymbal through the headphones.
In the case of a singer, this solution works well, but only when the singer has a good voice to begin with. If the singer does not sound good, the end result is simply a louder version of an unpleasant voice.
The same problem arises in the case of a deadened cymbal. These cymbals do not sound nearly as good as the real thing. Although one can amplify the sound of a deadened cymbal, the result will just be a louder deadened cymbal. Since cymbals often play the role of an exclamation point in a musical composition, the whimper of a deadened cymbal trying to rise to the occasion by mere amplification can be unsatisfying.
It is possible, of course, to carry out some rudimentary signal processing procedures on the sound of a deadened cymbal. However, these techniques are best used to enhance something that already sounds reasonably good to begin with.